Optical fibers and fiber gratings are useful for telecommunication transmission and networking. In long-distance transmission of optical signals, the accumulation of signal dispersion may be a serious problem. This problem intensifies with an increase in the distance the signals travel and the number of channels in a wavelength-division-multiplexed (WDM) optical communication system. Efforts to compensate for chromatic dispersion to date have involved use of dispersion compensating fibers, dispersion compensating gratings, or a combination of both. See M. I. Hayee et al., IEEE PHOTONICS TECHNOLOGY LETT., Vol. 9, No. 9, p. 1271 (1997); R. I. Laming et al., IEEE PHOTONICS TECHNOLOGY LETT., Vol. 8, No. 3 (1996); W. H. Loh et al., IEEE PHOTONICS TECHNOLOGY LETT., Vol. 8, No. 7 (1996); K. O. Hill et al., OPT. LETT., Vol. 19, p. 1314 (1994); and U.S. Pat. No. 5,701,188 issued to M. Shigematsu et al., on Dec. 23, 1997, incorporated herein by reference.
The above-mentioned dispersion compensating devices, however, are not flexible and provide only a fixed degree of compensation for chromatic dispersion. Those concerned with technologies involving optical communications systems continue to search or new designs enabling for more flexible methods for compensating for chromatic dispersion. It is desirable to have a tunable dispersion compensator whose characteristics and performance may be selectively altered and that does not require a continuous use of power. This invention discloses such a tunable dispersion compensator and optical communication systems comprising such a compensator.